NMR Spectroscopy will continue to be applied to determine the structure and dynamics of transfer RNA in interaction with the enzyme aminoacyl tRNA synthetase. These two macromolecules are essential parts of the biosynthetic machinery of all living things. The emphasis is on use of isotope labels of 15N and 13C to highlight proton NMR signals and provide more information than straight NMR spectroscopy. Smaller molecules interacting with the enzyme, as well as labelled enzyme and labelled tRNA, will be examined to provide information on molecular changes during function of the molecules. The NMR methods being used are prototypical of methods potentially applicable to drug design.